Run an online shell script the next time a PC checks in

I have a script that I need to run on all PCs in the organization. I set it up as an online shell script with an associated Windows batch file to force the update of some software. I managed to run the script but it only worked for those PCs that happened to be connected when I set the script to run. What do I need to do to get the PCs to run this script the next time they check in?